The invention relates to a vibration damper having: a damper tube filled with a damping medium; a piston rod which can move in an oscillating and reciprocal manner in the damper tube and one end of which protrudes into the damper tube and which comprises at this end a piston rod extension and a shoulder; a piston which divides the interior of the damper tube into a working chamber remote from the piston rod and a piston rod-side working chamber and which is disposed coaxially with respect to the piston rod extension and comprises restrictor openings and at least one spring washer covering these restrictor openings in each working chamber; a buffer spring disposed in the piston rod-side working chamber; and also a spring collar which is disposed in the piston rod-side working chamber and has a first support surface supporting the buffer spring and a second support surface for the at least one spring washer disposed in the piston rod-side working chamber.
A vibration damper of this type is known from DE 196 26 143 C2. In this known vibration damper a buffer in the form of a buffer spring is disposed in the upper working chamber concentrically with respect to the piston rod. The buffer spring is centred in the guiding direction of the piston rod by a spring collar which can possibly comprise an inner slip ring in order to allow only minimal frictional forces to occur during relative movement with respect to the piston rod. The other end of the buffer spring lies against a bearing of a disc body. This disc body forms the spring collar in terms of the present invention and is braced on a pin of the piston rod together with the piston. The disc body comprises, on its side remote from the buffer spring, a support surface for the spring washers disposed in the piston rod-side working chamber.
A disadvantage in the known vibration damper resides in the fact that forces exerted by the buffer spring onto the disc body (the spring collar) are introduced directly into the working piston via the piston rod-side spring washers. As a result, the damping characteristic of the damping piston is negatively influenced. Furthermore, the forces exerted by the buffer spring onto the disc body (the spring collar) flow into the pin of the piston rod via the working piston which can lead to problems in terms of stability in the region of the pin. In extreme cases, deformation or even separation of the pin can occur in the case of high buffer forces.